1. Field of the Invention
The present invention relates to a video signal processing apparatus that processes both a progressive scanning video signal and a conventional interlace scanning video signal.
2. Description of the Related Art
Generally, when a 24 fps (frames per second) movie, for example, is converted into a video signal so-called telecine signal, two or three fields of the video signal are composed of one frame of the movie. This format is referred to as 3-2 pulldown format. When such a video signal is displayed on a progressive scanning TV receiver, with information that represents which field is generated with which frame, scan lines can be properly interpolated. Thus, the picture quality of the video signal is improved. FIG. 9(a) shows a scan line interpolating process in the case of a 24 fps film. FIG. 9(b) shown a scan line interpolating process in the case of a 30 fps film.
With signals of two fields generated with the same frame, an inter-field interpolating process is performed. To do that, it is necessary to know which field is generated with which frame. When the current field is generated with the same frame as the preceding field, "same frame" information is transmitted as pulldown information. In contrast, when the current field is generated with the different frame as the preceding field, "different frame" information is transmitted as pulldown information.
A pulldown transmitting method has been defined in "Video ID signal transmitting method", Engineering Report EIAJ CPR-1204, Electronic Industries Association of Japan, May 1997. According to the method, the pulldown information is transmitted as "same frame" information when the current field is generated with the same frame as the preceding field. In contrast, the puildown information is transmitted as "different frame" information when the current field is generated with the different frame as the preceding field. With the pulldown information, a telecine video signal can be converted into a progressive scanning signal with high quality.
However, according to the CPR-1204 standard, it is not necessary to transmit pulldown information in each field. In addition, another information can be transmitted along with the pulldown information. In this case, such an area should be sequentially processed.
Thus, when a telecine signal is continuous, no problem takes place. However, when there are both a telecine signal and a conventional interlace scanning signal, the pulldown information cannot be effectively used.